Conventionally, a layout of a semiconductor device, e.g., an SRAM, using Multi-Gate Field Effect Transistor (MuGFET) technology is conducted in a non-Manhattan layout. Portions of the layout must be rotated by 45° to accommodate for the conductivity of the substrate surface.
FIG. 1 shows a conventional layout for a MuGFET.
In particular, a MuGFET 100 is constructed of a fin 130 straddled by a gate or notch 120. The fin 110 and notch 120 are formed over a semiconductor substrate 140, e.g., SiO2.
The MuGFET 100 channels are on the sidewalls 150 of the fin 130. For a normal <110> notch (001) surface wafer, the sidewall 150 of the fin 130 are (110) if a fin 130 is laid at 0 or 90 degree rotations with respect to the notch 120. If the rotation of the fin 130 with respect to the notch 120 is 45 degrees, the fin 130 sidewalls 150 are (100).
The (110) surface is good for hole mobility but poor for electron mobility, while the (100) surface is poor for hole mobility but good for electron mobility. To gain access to both surfaces, mixed rotations of the fins 130 with respect to notches 120 of 0 and 45 degrees are necessary. Such mixed rotations increase the layout area of an integrated circuit device by approximately 25% and increase lithography difficulties.
FIG. 2 shows an example top-level view of a non-Manhattan layout of a static random access memory (SRAM) relying on MuGFET technology.
In particular, example SRAM 200 is constructed of a plurality of fins 210 and notchs 220. The fins 210 are connected to other components of the SRAM 200 through contact patches 215. The notches 220 are connected to other components of the SRAM 200 through contact patches 225.
Measurements for the example SRAM 200 are taken from a centerline of the fin contact patches 215 and the centerline of the notch contact patches 225. Using industry standards for spacing between the various components of SRAM 200, the dimensions for the example SRAM 200 are approximately 500 nm by approximately 812.5 nm. Thus, the layout area for the example SRAM 200 is approximately 406,250 nm2.
Accordingly, the present teachings solve these and other problems of the prior art's problems with laying out a MuGFET based semiconductor device.